Chicken and Mushrooms en Papillote

To prepare the chicken breasts: Fill a large bowl with cold water. Cut a thin slice off the stem of each mushroom. Working a handful at a time, dip mushrooms in the water, swishing them around to clean them, then lift out and drain on towels. Rinse quickly; do not let the mushrooms soak or they will absorb water.

Heat the chicken stock and butter in a large saute pan or skillet over medium-high heat. Saute the mushrooms, stirring them frequently with a wooden spoon, until they begin to color. Sprinkle sea salt to taste over the mushrooms and cover the pan with a plate; cook 2 minutes, until the mushrooms have cooked through and rendered their juice. Strain, reserving both the mushrooms and juice. Reserve half the chanterelles whole; cut the remaining chanterelles in 1/4-inch dice. If necessary, saute the chanterelles in batches, dividing the stock and butter among the batches.

Cut away all but the last, heaviest joint of the wing on each breast. Remove the remaining bones. Spread out the meat on one breast and sprinkle with sea salt. Spoon one-fourth of the minced shallots and mushroom dice along the center of the meat. Drizzle each with a tablespoon of mushroom juice. Dot with a tablespoon of butter, then fold over and press the edges to seal. Repeat with all breasts and stuffing.

Preheat the oven to 375 F. Cut four 18-inch squares of heavy aluminum foil. Cut half of the reserved chanterelles in half; set aside the whole ones which remain. Spread out the foil pieces, shiny-side down. Put a filled chicken breast on the lower half of each. Top with a tablespoon of butter and a few halved chanterelles. Fold the foil over a breast, then fold one short edge of the foil over itself twice. Fold the long edge of the foil over itself twice, then the final short edge. Fold over the spine edge. Press the edges to seal. Repeat to make four packets. Place the packets in a roasting pan and add hot water to nearly cover the packets. Bake 15 minutes. Remove from the oven; lift the packets from the pan.

To prepare the sauce: Combine the remaining mushroom juice, foie gras, and butter in a medium saute pan or skillet. Bring to a boil over medium heat, stirring gently with a whisk. Reduce the heat to medium-low and cook 3 to 4 minutes, until reduced by one-third in volume. Open the foil packets and pour the cooking juices into the sauce. Strain the sauce through a fine-meshed sieve; season to taste with pepper.

Return the reserved whole chanterelles and the minced shallot and parsley into a small saute pan and warm with 2 tablespoons of butter.

To serve: Slice each chicken crosswise into medallions, keeping the pieces of each breast together. Slip a large knife under the slices of one chicken breast and lift it in one piece; place on a bed of mushrooms. Repeat with the remaining breasts. Spread the whole mushrooms beside and over the chicken pieces. Spoon sauce over the chicken and mushrooms.